For hemodialysis and other medical procedures, there is the need for chronic, repeated access to the vascular system of a patient. For example, in hemodialysis, access to the patient""s blood stream is required generally about three times a week.
Conventionally, this may be accomplished by forming a fistula in an extremity of the patient such as the arm, where an artery and vein of the arm are interconnected. The arterial pressure causes the arm veins to balloon out, and to become good targets for fistula needles, which are commonly straight, sharp needles connected to a length of flexible tubing which, in turn, is connected to an arterial or venous hemodialysis set during use. Alternately, a trocar bearing catheter is used for blood access. The sharp stylet (within a rigid or flexible, dull cannula) provides the cutting means to enter the fistula. Then the sharp, typically hollow-bore trocar is removed leaving the blunt cannula in the vessel.
Two such needle sticks are typically required in a hemodialysis procedure, one for the arterial side, and the other for the venous side, i.e, one to obtain blood from the patient and another to return blood back to the patient.
Significant disadvantages exist with such fistula techniques. Particularly, a direct inter-connection between an artery and a vein places a burden on the patient of the need for additional cardiac output, since some blood is not passing through the capillary system of the body or effectively delivering its oxygen into the tissues.
Accordingly, another type of vascular access is provided, namely implantable vascular access devices such as the vascular device shown in Finch et al. U.S. Pat. No. 5,562,617, Prosl, et al U.S. Pat. No. 4,569,675, and also other known designs of vascular access device. Such a device may comprise an implantable fluid chamber which is connected to a catheter, the system being connected to a vein. Vascular access is provided by a needle which penetrates the skin, and then couples with a port of the fluid chamber, to form an access flow path with the vascular system of the patient through which blood may be removed or replaced. This kind of system has an advantage in that, when it is not connected with a needle, there is no shunting between the arterial and venous system of the patient.
Typically, when a needle does enter such an implanted vascular chamber, it does so at an angle to the skin, from 30xc2x0 in some devices up to vertical. Accordingly, there is significant advantage in using a needle set in which the needle extends transversely to its set tubing, so that the needle can penetrate the skin in substantially vertical manner, but the set tubing can be basically parallel to the skin. The prior art discloses 90xc2x0 bent needles for subcutaneous chemotherapy port access devices.
By this invention, an improved set with an angled needle is provided, exhibiting significant advantage of use as a needle for access to a permanently implanted vascular access chamber, to facilitate easy and reliable vascular access.
Another preferred object of this invention is the pre-connection of the needle to a blood tubing set. In the prior art of fistula needles or catheters for access to ports or AV fistulas, the needle set must be a separate device from the blood tubing set. This is required because a xe2x80x9cclot wormxe2x80x9d must be removed via the female luer that is the proximal termination of such device. Similarly, the xe2x80x9cheparin lockxe2x80x9d must be delivered through this female luer. Only after these preparation steps are finished can the fistula needle set be joined to the blood tubing set.
Also, it is well known that sharp needles which are brought into contact with blood are potentially dangerous in the event that the needle accidentally sticks a health worker or another person, since this can facilitate the transfer of blood-borne diseases.
Utterberg et al. U.S. Pat. No. 5,112,311 discloses a needle protector comprising a slotted needle sheath which slides longitudinally in the direction of the needle axis along the wings of winged fistula needles, to be advanced into a position that encloses the needle tip as the needle is being withdrawn from a patient. By this invention, sliding or rotating protector systems for angled needles are provided to protect medical personnel and others from accidental needle stick of angled needles, particularly after they have been used in contact with blood.
A needle-containing set is disclosed for fluid-flow connection with the vascular system of a patient. Typically but not necessarily, the connection is through an implanted fluid chamber connected to the vascular system of a patient.
This set comprises a hollow, hypodermic needle having a typical sharp end for skin penetration and connection with the vascular system.
In an alternate catheter form the set comprises a hollow cannula typically unpointed and dull at the end. Within this cannula is a sharp, hollow bore trocar, the point of which extends beyond the end of the cannula for needling.
The sharp needle or dull cannula is connected to a hollow hub at its end opposed to its sharp end. A fluid flow port is defined in the hub at a position which is laterally spaced from the axis of the needle. Typically, the fluid flow port is surrounded by a connector of the hub, typically a sleeve, which extends transversely at an angle to the needle axis, providing an angled aspect to the needle and hub. The connector is generally connected to a length of flexible tubing to provide a complete needle set.
Also, an injection site aperture is defined in the hub at a position which is centrally intersected by the needle axis. The injection site aperture is closed by a recloseable, needle-penetrable wall, which generally may be of conventional design, made of an elastomeric material, and optionally defining a recloseable slit so that it may be penetrated by a blunt member as well as by a needle.
In the case of the previously described alternate catheter set, the trocar""s proximal end passes through the injection site, and is removed after needling.
The term xe2x80x9csetxe2x80x9d implies a needle and hub connected to conventional and optional tubing, set connectors, branch connectors, branch lines, connected pump tubing, bubble traps, and the like, as may be needed for a desired medical purpose. Such connection may be permanent or via connectors such as male/female reversible fittings.
One significant advantage of this system pertains to the issue of the removal of a xe2x80x9cclot wormxe2x80x9d from a hemodialysis catheter which is permanently implanted in a vein of a patient, and connected to an implanted, needle-pierceable fluid chamber. Typically, when a conventional fistula needle is brought into contact with such a hemodialysis catheter, the first thing that must be done is the removal of the xe2x80x9cclot wormxe2x80x9d. The clot worm is the length of clotted blood which has formed inside of the implanted venous catheter in the period of time that has elapsed since the last dialysis procedure. This must be sucked out with a syringe.
In conventional needle sets, the syringe is applied to an opposed end of the set which connects with the needle at its other end. This results in a significant waste of blood because of the significant spacing between the syringe and the needle, which spacing is created by the flexible tubing of a conventional needle set. However, by this invention, access is provided to the needle through the injection site aperture, which is defined in the hub of the set of this invention at a position centrally intersected by the needle axis. A syringe with an attached needle or blunt tube can be passed through the recloseable, needle-penetrable wall provided, and the clot worm can be removed at that position, which is considerably nearer to the needle itself (or even positioned within the needle), than is a connector of a conventional fistula needle, where the needle and connector are positioned at opposite ends of a length of tubing, on the order of one foot in length. Because of this, there can be less loss of blood in the removal of the clot worm by this invention, since the clot worm is removed from a position at the needle hub, rather than from a position which is substantially spaced by a length of tubing from the needle hub. Similarly, less heparin is needed to provide a xe2x80x9cheparin lockxe2x80x9d to an implanted catheter or the like, using a needle of this invention.
Also, a straight probe may be advanced through the needle of this invention without disconnecting the needle from the set.
It is desirable for a needle point protector to be carried by or added to the needle set of this invention so that the users and handlers of the set are protected from accidental needle stick, especially after the needle has been in contact with blood.
One way of accomplishing this is to provide an elongated housing, open at one side, which is pivotally attached to the hub to move between a position spaced from the needle and a position where at least the needle sharp end is positioned within the housing, so that the sharp end is shielded to reduce the risk of accidental needle sticks.
As another system for protecting users against the needle, a blunt, rigid or flexible rod or tube may be placed to extend through the recloseable needle-penetrable wall, and also through the hollow needle itself, to extend at least effectively beyond the sharp end. In the previously described alternate catheter set the blunt rod would pass through a hollow trocar. This provides protection from accidental needle sticks, since the rod or tube substantially fills the bore of the needle and thus provides to the needle a blunt end rather than a sharp end while it is present. Also, the probe tip may be radially expandable, containing a rubber O-ring or a resilient umbrella shape, to expand outwardly for added protecting action of users from the sharp needle tip when the rod or tube is advanced out of the needle beyond the needle tip.
As another embodiment of a needle protector, a tube may be longitudinally and slidably mounted on the hub in a position which is substantially coaxial with the needle. The tube defines a longitudinal slot. The sleeve which surrounds the fluid flow port extends through the slot, and thus carries the tube in longitudinally slidable manner.
Preferably, most of the slot is narrower than the sleeve for restrictive retention, but is outwardly expandable by resilient bending of the tube to allow sliding of the tube along the sleeve. Preferably, the slot comprises a first, enlarged portion positioned for receiving the sleeve with the tube retracted to expose the needle. The slot also defines a second, enlarged portion which is positioned for receiving the sleeve in a position where the tube encloses the needle sharp end. Thus, the tube may be longitudinally moved from a position where the needle is exposed, to a position where the needle is recessed within the tube, with the position being retained by snap-fit action created by the resilient resistance of the sleeve to the expansion of the slot, so that the sleeve encloses the sharp needle end until the set can be disposed of
Thus, a needle is provided, having substantial advantages when compared with corresponding fistula needles and other needles of the prior art. The needles and sets of this invention may be used with other medical procedures than hemodialysis, for example, peritoneal dialysis, angiography, angioplasty, hemoperfusion, chemotherapy, and the like.
In another embodiment of this invention, a set for fluid flow connection with the vascular system of a patient is provided, with the set comprising a hollow cannula having a bore and a longitudinal axis. The cannula may be blunt if desired, contrary to the needle of the previous embodiment, but the cannula is for skin penetration and connection with the vascular system. A hollow hub carries the cannula, with a fluid flow port defined in the hub at a position laterally spaced from the axis of the cannula, in a manner similar to the previous embodiment. An access site aperture is defined in the hub at a position centrally intersected by the cannula axis. The access site aperture is closed by a recloseable, penetrable wall.
In this embodiment, a tubular, sharp-ended trocar extends through the recloseable, penetrable wall and the bore of the cannula. By this invention, a blunting rod extends through the lumen defined by the tubular trocar. The blunting rod has a blunt end that projects outwardly beyond the sharp end of the trocar. Thus, the chances of injury caused by the sharp end of the trocar can be greatly reduced when the blunt end of the blunting rod projects outwardly beyond the trocar sharp end.